Recent advances in TROPOMI-based methane source detection: a systematic review

The renewed increase in atmospheric methane (CH4) concentrations since 2007, culminating in record growth rates in 2021, poses a critical challenge to achieving global climate targets. The TROPOspheric Monitoring Instrument (TROPOMI) onboard the Sentinel-5 Precursor satellite provides unprecedented daily global observations of CH4 at a spatial resolution (7 × 7 km2, improved to 5.5 × 7 km2 since August 2019), enabling substantial advances in space-based CH4 monitoring and emission quantification. Here, we synthesize and categorize 133 published studies spanning global, regional and local scales and covering both anthropogenic and natural CH4 sources. Collectively, these studies demonstrate TROPOMI's capability to quantify emissions across diverse spatiotemporal scales, as well as its synergy with other satellite instruments for detecting and attributing facility-level sources, such as fossil fuel infrastructure and landfills. However, emission estimates remain challenged by uncertainties in column-averaged CH4 (XCH4) retrievals related to surface albedo effects and persistent cloud cover, particularly in tropical and high-latitude regions. These limitations can be mitigated through improved retrieval algorithms, refined quality filtering, multisatellite fusion, and integration with ground-based observations and airborne campaigns. Furthermore, we assess the suitability of different quantification approaches for specific source types, such as Gaussian plume models for large isolated emitters and inverse modeling for spatially diffuse emissions. Finally, we outline key methodological priorities and opportunities in the context of the recent MetOp-SG-A satellite, which will complement TROPOMI with a morning overpass. By consolidating current applications of TROPOMI XCH4 observations, this review provides guidance for enhancing space-based methane monitoring and supports targeted mitigation strategies aligned with achieving Sustainable Development Goal 13.

自2007年以来，大气甲烷（CH₄）浓度再度回升，并于2021年达到创纪录的增速，这对实现全球气候目标构成了严峻挑战。搭载于哨兵-5先导卫星（Sentinel-5 Precursor）的对流层监测仪（TROPOspheric Monitoring Instrument, TROPOMI）可提供前所未有的全球每日甲烷观测数据，其空间分辨率为7×7 km²，自2019年8月起提升至5.5×7 km²，为天基甲烷监测与排放量化研究带来了显著进展。本文整合并分类了133项已发表的研究，这些研究覆盖全球、区域与局地尺度，涵盖人为源与自然源两类甲烷排放源。综合来看，这些研究证实了TROPOMI具备在多样时空尺度下量化甲烷排放的能力，同时证明其可与其他卫星仪器协同，用于探测并归属设施级排放源，例如化石燃料基础设施与垃圾填埋场。然而，排放估算仍受限于柱平均甲烷（XCH4，column-averaged CH₄）反演过程中的不确定性，这类不确定性与地表反照率效应及持续云覆盖相关，在热带与高纬度地区尤为显著。通过优化反演算法、改进质量过滤流程、应用多卫星融合技术，以及结合地基观测与机载观测任务，此类局限性可得到有效缓解。此外，本文评估了不同量化方法针对特定排放源类型的适用性，例如针对大型孤立排放源的高斯烟羽模型，以及针对空间弥散排放的反演建模方法。本文最终概述了新一代MetOp-SG-A卫星背景下的关键方法学优先级与发展机遇，该卫星将通过上午过境轨道补充TROPOMI的观测能力。本文通过整合TROPOMI XCH4观测的当前应用，为提升天基甲烷监测能力提供了指导，并助力制定契合可持续发展目标13（Sustainable Development Goal 13）的针对性减排策略。